1. Field of the Invention
The subject invention pertains to the art of communication systems and specifically to an optical communication system wherein data signals are relayed from station to station along predetermined routes.
2. Description of the Prior Art
Optical communication repeater systems generally comprise a multiplicity of repeater stations whereby communications between the central station and other stations within the system are accomplished by relaying the data from station to station. This is accomplished by supplying each station with an optical receiver which receives a signal from a station prior in line and an optical transmitter which transmits an amplified or reconstructed signal to a station subsequent in line. To provide two way reception and transmission, each station must be equipped with two such receivers and transmitters thereby enabling a dialogue between the central station and each of the outlying stations. At installation, the receivers and transmitters at each station are pointed toward transmitters and receivers of prior and subsequent stations by means of aiming telescopes sighted thereto. Generally, the alignment telescope and optical transmitter and optical receiver and the associated electronics are in a common package, and considerable effort is required to align the three elements to one another. To facilitate aiming during installation, the package is typically fitted with an external two-axis swivel or gimbal together with a fine adjusting and locking mechanism. In a typical installation, two such packages are mounted back to back on a mast to provide unobstructed lines of sight. Thus, not only are two complete units required for each station but electronic servicing difficulties are encountered due to this mast mounting. The present invention reduces costs, increases system reliability, minimizes the mast mounted equipment and installation time, and provides increased electronic serviceability.